Method and device for determining instantaneous sediment flux of lower-level sediment preparation under action of waves

Abstract

The invention provides a method and a device for determining instantaneous sediment flux of graded sand under the action of waves. The method comprises the following steps: acquiring sediment settling velocities, exposure hiding factors, phase difference parameters and wave boundary layer thicknesses of different components in graded sand; and calculating the instantaneous sediment flux of the graded sand based on the sediment settling velocity, the exposure hiding factor, the phase difference parameter and the thickness of the wave boundary layer. According to the method, design calculation is carried out through parameters such as the obtained sediment settling velocity, the exposure hiding factor, the phase difference parameter and the wave boundary layer thickness, the instantaneous sediment flux of all components in the graded sand and the instantaneous sediment flux of the graded sand can be calculated, and the exposure hiding effect between the different components in the graded sand can be reflected in the process; the time response required by the sediment flux relative to a hydrodynamic condition and net flow caused by asymmetry of a boundary layer can be reflected, error estimation of the instantaneous sediment flux of the graded sand is avoided, and the estimation precision of the instantaneous sediment flux of the graded sand is improved.

Description

Technical Field

[0001] The invention relates to the technical field of water conservancy engineering, and in particular to a method and a device for determining instantaneous sediment flux of graded sand under wave action. Background Art

[0002] The periodic reciprocating wave motion makes the sediment movement in the coastal zone have the characteristics of non-constant, non-saturated and unbalanced transport.

[0003] Most of the sediment in nature is graded sand. The exposure, hiding, coarsening and other effects between different components in graded sand will affect wave dissipation, coastal and cross-shore sediment transport, sorting, bed roughness and beach evolution.

[0004] Instantaneous sediment flux is the product of sediment concentration and velocity, which indicates the amount of sediment passing through a unit section per unit time.

[0005] At present, the instantaneous sediment flux widely used in engineering is derived based on the theory of uniform sand steady flow, but it does not take into account the grading effect, phase difference and boundary layer asymmetry. This will result in the sediment flux obtained being unable to reflect the transport characteristics of different particle size components in the graded sand, and unable to reflect the exposure and hiding effects between different components in the graded sand, that is, the promoting effect of fine components on coarse components and the inhibiting effect of coarse components on fine components. It also cannot reflect the time response required for sediment flux relative to hydrodynamic conditions, nor can it reflect the net flow caused by boundary layer asymmetry.

[0006] Therefore, it is very necessary to solve the problem that the existing instantaneous sediment flux determination method does not take into account the grading effect, phase difference and boundary layer asymmetry, resulting in low accuracy of the instantaneous sediment flux. Summary of the invention

[0007] The present invention provides a method and device for determining the instantaneous sediment flux of graded sand under wave action, so as to overcome the defect that the existing instantaneous sediment flux determination method does not take into account the grading effect, phase difference and boundary layer asymmetry, resulting in low accuracy of the instantaneous sediment flux. The method can not only reflect the exposure and hiding effects between different components in the graded sand, but also reflect the time response of the sediment flux relative to the hydrodynamic conditions and the net flow caused by the boundary layer asymmetry, thereby further improving the estimation accuracy of the instantaneous sediment flux of the graded sand.

[0008] On the one hand, the present invention provides a method for determining the instantaneous sediment flux of graded sand under the action of waves, comprising: obtaining the sediment settling velocity, exposure and hiding factors, phase difference parameters and wave boundary layer thickness of different components in the graded sand; based on the sediment settling velocity, exposure and hiding factors, phase difference parameters and wave boundary layer thickness, calculating the instantaneous sediment flux of the graded sand.

[0009] Furthermore, the instantaneous sediment flux of graded sand is calculated based on the sediment settling velocity, exposure and hiding factor, phase difference parameter and wave boundary layer thickness, including: calculating the sediment amount of different components in the graded sand according to the sediment settling velocity, exposure and hiding factor and phase difference parameter; calculating the sediment concentration of different components in the graded sand according to the sediment amount of different components in the graded sand, and determining the erosion depth of the moving bed of the graded sand; calculating the moving bed surface flow velocity according to the erosion depth of the moving bed of the graded sand and the wave boundary layer thickness; calculating the instantaneous sediment flux of the graded sand under the action of waves according to the moving bed surface flow velocity and the sediment concentration of different components in the graded sand.

[0010] Furthermore, the instantaneous sediment flux of the graded sand under the action of waves is calculated according to the flow velocity of the moving bed surface and the sediment concentration of different components in the graded sand, which includes: classifying the graded sand moving bed surface and graded sand components according to the erosion depth of the graded sand moving bed surface and the sediment amount of different components in the graded sand; wherein the categories of the graded sand moving bed surface include free sand-containing layers, sand storage layers and immovable sand-containing layers, and the graded sand components include first-type graded sand components and second-type graded sand components.

[0011] Furthermore, the instantaneous sediment flux of the graded sand under the action of waves is calculated according to the moving bed flow velocity and the sediment concentration of different components in the graded sand, including: calculating the instantaneous sediment flux of different components in the graded sand according to the moving bed flow velocity, the sediment concentration of different components in the graded sand and the type of the moving bed of the graded sand; calculating the instantaneous sediment flux of the graded sand under the action of waves according to the instantaneous sediment flux of different components in the graded sand.

[0012] Furthermore, the instantaneous sediment flux of the first graded sand component is calculated by the following formula:

[0013]

[0014] The instantaneous sediment flux of the second graded sand component is calculated by the following formula:

[0015]

[0016] Among them, Q i1 is the instantaneous sediment flux of the first graded sand component, z is the vertical coordinate, t is the time, u B is the velocity of the moving bed, C i is the sediment concentration of component i in the graded sand, Δ is the erosion depth of the graded sand moving bed, Q i2 is the instantaneous sediment flux of the second graded sand component, Δ i is the sediment content of component i in the graded sand, C m is the maximum volume concentration.

[0017] Furthermore, the moving bed surface flow velocity u B Calculated by the following formula:

[0018]

[0019] Among them, u is the velocity of the outer boundary layer, u0 is the velocity amplitude of the outer boundary layer, r is the nonlinear index, δ B is the thickness of the wave boundary layer, t0 is the parameter that makes u(0) = 0, α = 2π / T is the frequency, is the waveform parameter;

[0020] The sediment concentration C of the graded sand components i Calculated by the following formula:

[0021]

[0022] Furthermore, the wave boundary layer thickness δ B It is obtained by the following calculation formula:

[0023] δ B =0.09A 0.82 k N 0.18

[0024] Where A is the orbital amplitude of the wave, k N It is the roughness height of the graded sand moving bed.

[0025] In a second aspect, the present invention also provides a device for determining the instantaneous sediment flux of graded sand under the action of waves, comprising: a data acquisition module for obtaining the sediment settling velocity, exposure and hiding factors, phase difference parameters and wave boundary layer thickness of different components in the graded sand; an instantaneous sediment flux calculation module for calculating the instantaneous sediment flux of the graded sand based on the sediment settling velocity, exposure and hiding factors, phase difference parameters and wave boundary layer thickness.

[0026] In a third aspect, the present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, it implements a method for determining the instantaneous sediment flux of graded sand under the action of waves as described in any one of the above.

[0027] In a fourth aspect, the present invention further provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements a method for determining instantaneous sediment flux of graded sand under wave action as described in any one of the above.

[0028] The present invention provides a method for determining the instantaneous sediment flux of graded sand under the action of waves, by obtaining the sediment settling velocity, exposure and concealment factor, phase difference parameter and wave boundary layer thickness of different components in the graded sand, and based on the sediment settling velocity, exposure and concealment factor, phase difference parameter and wave boundary layer thickness, the instantaneous sediment flux of the graded sand is calculated. The method is designed and calculated by obtaining parameters such as sediment settling velocity, exposure and concealment factor, phase difference parameter and wave boundary layer thickness, and the instantaneous sediment flux of each component in the graded sand and the total instantaneous sediment flux of the graded sand can be calculated. This process can not only reflect the exposure and concealment effect between different components in the graded sand, but also reflect the time response of the sediment flux relative to the hydrodynamic conditions and the net flow caused by the asymmetry of the boundary layer, thereby avoiding the wrong estimation of the instantaneous sediment flux of the graded sand and further improving the estimation accuracy of the instantaneous sediment flux of the graded sand. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 A schematic flow chart of a method for determining instantaneous sediment flux of graded sand under wave action provided by the present invention;

[0031] Figure 2 A schematic diagram of the changes in the wave track amplitude, the roughness height of the moving bed surface, the Schertz number and the wave friction factor within the wave cycle provided by the present invention;

[0032] Figure 3 A schematic diagram of the change of the erosion depth of the graded sand moving bed surface, the wave boundary layer thickness and the amount of sediment of different components in the graded sand during a wave cycle provided by the present invention;

[0033] Figure 4 A schematic diagram of the flow velocity on the moving bed surface and the sediment concentration corresponding to different components in graded sand within a wave cycle provided by the present invention;

[0034] Figure 5 A schematic diagram of the changes of the first-type graded sand components and the second-type graded sand components provided by the present invention within a wave cycle;

[0035] Figure 6 A schematic diagram of the change of instantaneous sediment flux of graded sand provided by the present invention within a wave cycle;

[0036] Figure 7A schematic diagram of the changes in the sediment amounts of different components and the period-averaged sediment concentration within a wave cycle in the graded sand with the gradation effect removed provided by the present invention;

[0037] Figure 8 A schematic diagram of the structure of a device for determining instantaneous sediment flux of graded sand under wave action provided by the present invention;

[0038] Fig. 9 This is a schematic structural diagram of an electronic device provided by the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] It should be noted that the instantaneous sediment flux widely used in engineering is currently derived based on the theory of uniform sand steady flow, but it does not take into account the grading effect, phase difference and boundary layer asymmetry.

[0041] In other words, the sediment flux calculated by the existing technology cannot reflect the transport characteristics of different particle size components in the graded sand, cannot reflect the exposure and hiding effects between different components in the graded sand, that is, the promoting effect of fine components on coarse components and the inhibiting effect of coarse components on fine components, and cannot reflect the time response of sediment flux relative to hydrodynamic conditions, nor can it reflect the net flow caused by boundary layer asymmetry.

[0042] So far, there is no reference result or method on how to calculate the instantaneous sediment flux of graded sand under the action of waves.

[0043] In view of this, the present invention provides a method for determining the instantaneous sediment flux of graded sand under wave action, specifically, Figure 1 The schematic diagram shows the flow chart of the method for determining the instantaneous sediment flux of graded sand under the action of waves provided by the present invention.

[0044] like Figure 1 As shown, the method includes:

[0045] S110, obtaining sediment settling velocity, exposure and hiding factor, phase difference parameter and wave boundary layer thickness of different components in graded sand.

[0046] It can be understood that in this embodiment, in order to calculate the instantaneous sediment flux of graded sand under the action of waves, it is necessary to first execute step S110, that is, to obtain the sediment settling velocity, exposure and concealment factor, phase difference parameter, and wave boundary layer thickness of different components in the graded sand.

[0047] By obtaining the sediment settling velocity and exposure hidden factor of different components in graded sand, the grading effect is taken into consideration when calculating the instantaneous sediment flux of graded sand. Therefore, the instantaneous sediment flux of graded sand calculated subsequently can reflect the mutual influence between different components, reflecting the promoting effect of fine components on coarse components, and the inhibiting effect of coarse components on fine components.

[0048] By obtaining the phase difference parameters of different components in graded sand, the phase difference is taken into consideration when calculating the instantaneous sediment flux of graded sand, so that the instantaneous sediment flux of graded sand calculated subsequently can reflect the time response required for sediment movement relative to hydrodynamic conditions.

[0049] At the same time, by obtaining the wave boundary layer thickness, the boundary layer asymmetry is taken into consideration in calculating the instantaneous sediment flux of graded sand, so that the subsequent calculated instantaneous sediment flux of graded sand can reflect the net flow caused by the boundary layer asymmetry.

[0050] Among them, the process of obtaining the sediment settling velocity, exposure and concealment factor, phase difference parameter and wave boundary layer thickness of different components in the graded sand will be further expanded in the subsequent embodiments and will not be described in detail here.

[0051] S120, calculates the instantaneous sediment flux of graded sand based on sediment settling velocity, exposure and concealment factor, phase difference parameter and wave boundary layer thickness.

[0052] It can be understood that, based on the sediment settling velocity, exposure and concealment factor, phase difference parameter and wave boundary layer thickness of different components in the graded sand obtained in step S110, step S120 can further calculate the instantaneous sediment flux of the graded sand under the action of waves according to a series of parameters obtained in step S110.

[0053] Specifically, first, the amount of sediment corresponding to different components in the graded sand is calculated according to the sediment settling velocity, exposure hiding factor and phase difference parameter; then, according to the amount of sediment corresponding to different components in the graded sand, the sediment concentration of different components in the graded sand is calculated, and, according to the amount of sediment corresponding to different components in the graded sand, the erosion depth of the moving bed of the graded sand is calculated.

[0054] Next, the velocity of the moving bed is calculated based on the erosion depth of the graded sand moving bed and the thickness of the wave boundary layer.

[0055] Finally, the instantaneous sediment flux of graded sand under wave action is calculated based on the sediment concentration of different components in the graded sand and the flow velocity on the moving bed.

[0056] Among them, the calculation of the sediment amount and sediment concentration corresponding to different components in the graded sand, as well as the calculation formulas for the erosion depth of the moving bed of the graded sand, the moving bed flow velocity, and the instantaneous sediment flux of the graded sand will be further expanded in subsequent embodiments and will not be described in detail here.

[0057] It should be noted that the method for determining the instantaneous sediment flux of graded sand under wave action provided in this embodiment is applied to conditions where graded sand exists near the coast, and is particularly suitable for application scenarios such as beach protection and shoreline reconstruction of graded sand coasts.

[0058] It should also be noted that the method for determining the instantaneous sediment flux of graded sand under wave action provided in this embodiment can assist in determining the vertical sediment exchange intensity in related issues such as nearshore sediment transport and beach evolution, and accurately reflect the vertical sediment exchange of different sand layers (such as free sand-containing layers, sand storage layers, and immobile sand-containing layers).

[0059] In this embodiment, the instantaneous sediment flux of graded sand is calculated by obtaining the sediment settling velocity, exposure and concealment factor, phase difference parameter and wave boundary layer thickness of different components in graded sand, and based on the sediment settling velocity, exposure and concealment factor, phase difference parameter and wave boundary layer thickness. This method can calculate the instantaneous sediment flux of each component in graded sand and the total instantaneous sediment flux of graded sand by designing and calculating the obtained parameters such as sediment settling velocity, exposure and concealment factor, phase difference parameter and wave boundary layer thickness. This process can not only reflect the exposure and concealment effect between different components in graded sand, but also reflect the time response of sediment flux relative to hydrodynamic conditions and the net flow caused by boundary layer asymmetry, avoiding the wrong estimation of instantaneous sediment flux of graded sand, and further improving the estimation accuracy of instantaneous sediment flux of graded sand.

[0060] On the basis of the above-mentioned embodiment, the sediment settling velocity, exposure and concealment factor, phase difference parameter and wave boundary layer thickness of different components in the graded sand are further obtained. This embodiment will expand the calculation process of this series of parameters.

[0061] For example, in a specific embodiment, the sediment settling velocity of different components in the graded sand is obtained, specifically, the sediment settling velocity w i It can be calculated by the following formula:

[0062]

[0063] Among them, σ g is the geometric standard deviation of graded sand, d mis the arithmetic mean particle size of graded sand, d i is the particle size of component i in the graded sand, ν is the kinematic viscosity coefficient of water, s is the ratio of the density of sediment to water, and g is the acceleration of gravity.

[0064] For example, in another specific embodiment, the exposure hidden factors of different components in the graded sand are obtained, specifically, the exposure hidden factor η i It can be calculated by the following formula:

[0065]

[0066] Among them, η i is the interaction factor of component i in the graded sand, N is the number of sediment components in the graded sand, p j is the proportion of sediment in component j in graded sand, d i is the particle size of component i in the graded sand, d j The sediment particle size of component j in the graded sand, i and j are two different components in the graded sand.

[0067] For example, in another specific embodiment, the phase difference parameters of different components in the graded sand are obtained. Specifically, the phase difference parameters can be calculated by the following formula:

[0068]

[0069]

[0070] β 2i =3.2-β 1i (5)

[0071] Among them, φ i , β 1i , β 2i is the phase difference parameter of component i in graded sand, σ=2π / T is the frequency, Θ mi is the Sheartz number Θ of component i in graded sand i The maximum value, w i is the sediment settling velocity of component i in graded sand, u m is the maximum value of the outer boundary layer velocity u, η i is the exposure and hiding factor of component i in graded sand, d i is the particle size of sediment of component i in the graded sand.

[0072] Among them, w i and η i They can be calculated by the above formulas (1) and (2) respectively.

[0073] In formula (3), θ mi is the Sheartz number Θ of component i in graded sandi The maximum value of the Scherz number Θ i It can be calculated by the following formula:

[0074]

[0075] Among them, f is the wave friction factor, u is the outer boundary layer velocity, s is the ratio of sediment to water density, and g is the gravitational acceleration.

[0076] In formula (6), the wave friction factor can be calculated by the following formula:

[0077]

[0078] Among them, A ac,at is the wave trajectory amplitude of the onshore acceleration section and the offshore acceleration section, T ac,at is the wave period of the onshore acceleration section and the offshore acceleration section, k N is the roughness height of the moving bed surface, T c,t is the wave period at the peak and trough, f ac,at is the wave friction factor in the onshore acceleration section and the offshore acceleration section, A dc,dt is the wave track amplitude during the onshore deceleration stage and the offshore deceleration stage, T dc,dt is the wave period of the onshore deceleration section and the offshore deceleration section, f dc,dt is the wave friction factor in the onshore deceleration section and the offshore deceleration section.

[0079] According to formula (7), the subscripts c and t represent the peak and trough moments; the subscripts ac, at, dc and dt represent the onshore acceleration segment, the offshore acceleration segment, the onshore deceleration segment and the offshore deceleration segment.

[0080] In formula (7), the wave track amplitude A ac,at , A dc,dt It can be calculated by the following formula:

[0081]

[0082] Among them, u c,t is the outer boundary layer velocity at the peak and trough moments.

[0083] Roughness height of moving bed surface k N It can be obtained by the following calculation formula:

[0084]

[0085] For another example, in another specific embodiment, the wave boundary layer thickness is obtained, specifically, the wave boundary layer thickness δ B It can be calculated by the following formula:

[0086] δ B =0.09A 0.82 k N 0.18 (10)

[0087] Where A is the orbital amplitude of the wave, k N It is the roughness height of the graded sand moving bed.

[0088] A and K N They can be calculated by the above formulas (8) and (9) respectively.

[0089] According to the above formulas (1)-(10), the sediment settling velocity, exposure and hiding factor, phase difference parameter and wave boundary layer thickness of different components in the graded sand can be calculated. Furthermore, based on the sediment settling velocity, exposure and hiding factor, phase difference parameter and wave boundary layer thickness, the instantaneous sediment flux of the graded sand can be calculated.

[0090] In this embodiment, the instantaneous sediment flux of graded sand is calculated by obtaining the sediment settling velocity, exposure and concealment factor, phase difference parameter and wave boundary layer thickness of different components in graded sand, and based on the sediment settling velocity, exposure and concealment factor, phase difference parameter and wave boundary layer thickness. This method can calculate the instantaneous sediment flux of each component in graded sand and the total instantaneous sediment flux of graded sand by designing and calculating the obtained parameters such as sediment settling velocity, exposure and concealment factor, phase difference parameter and wave boundary layer thickness. This process can not only reflect the exposure and concealment effect between different components in graded sand, but also reflect the time response of sediment flux relative to hydrodynamic conditions and the net flow caused by boundary layer asymmetry, avoiding the wrong estimation of instantaneous sediment flux of graded sand, and further improving the estimation accuracy of instantaneous sediment flux of graded sand.

[0091] On the basis of the above embodiments, further, based on the sediment settling velocity, exposure and hiding factors, phase difference parameters and wave boundary layer thickness, the instantaneous sediment flux of graded sand is calculated, including: calculating the sediment amount of different components in the graded sand according to the sediment settling velocity, exposure and hiding factors and phase difference parameters; calculating the sediment concentration of different components in the graded sand according to the sediment amount of different components in the graded sand, and determining the erosion depth of the moving bed of the graded sand; calculating the moving bed surface flow velocity according to the erosion depth of the moving bed of the graded sand and the wave boundary layer thickness; calculating the instantaneous sediment flux of the graded sand under the action of waves according to the moving bed surface flow velocity and the sediment concentration of different components in the graded sand.

[0092] It can be understood that after calculating the sediment settling velocity, exposure and hiding factor, phase difference parameter and wave boundary layer thickness of different components in the graded sand, the sediment amount of different components in the graded sand is first calculated based on the sediment settling velocity, exposure and hiding factor and phase difference parameter.

[0093] Specifically, the amount of sediment corresponding to different components in graded sand is Δ i It can be calculated by the following formula:

[0094]

[0095] Among them, σ = 2π / T is the frequency, t is the time, φ i , β 1i , β 2i is the phase difference parameter of component i in graded sand, Θ i is the Sheartz number of component i in graded sand, Θ mi is the Sheartz number Θ of component i in graded sand i The maximum value of u m is the maximum value of the outer boundary layer velocity u, w i is the sediment settling velocity of the graded sand components, η i is the exposure and hiding factor of component i in graded sand, d i is the particle size of sediment of component i in the graded sand.

[0096] Calculate the sediment volume Δ corresponding to different components in the graded sand i Afterwards, according to the sediment volume Δ corresponding to different components in the graded sand i , calculate the sediment concentration of different components in the graded sand. Specifically, the sediment concentration of different components in the graded sand C i It can be calculated by the following formula:

[0097]

[0098] Among them, C m is the maximum volume concentration, Δ i is the sediment amount of component i in the graded sand, z is the vertical coordinate, and t is the time.

[0099] In a specific embodiment, the maximum volume concentration C m The value is 0.6.

[0100] At the same time, according to the sediment volume Δ corresponding to different components in the graded sand i , calculate the erosion depth of the graded sand moving bed surface, and the erosion depth Δ can be calculated by the following formula:

[0101]

[0102] Where N is the number of sediment components in the graded sand, p i is the proportion of sediment in component i in the graded sand.

[0103] After determining the erosion depth of the graded sand moving bed, the moving bed flow velocity is calculated according to the erosion depth of the graded sand moving bed and the thickness of the wave boundary layer. Specifically, the moving bed flow velocity u B It can be calculated by the following formula:

[0104]

[0105] Among them, u is the velocity of the outer boundary layer, u0 is the velocity amplitude of the outer boundary layer, r is the nonlinear index, δ B is the wave boundary layer thickness, t0 is the parameter that makes u(0) = 0, σ = 2π / T is the frequency, is the waveform parameter, α is the phase advance parameter of the velocity and shear stress on the moving bed surface relative to the velocity of the outer boundary layer, u, u0, r, t0 and All are known values.

[0106] In a specific embodiment, the phase advance parameter α takes a value of 0.32.

[0107] After calculating the moving bed velocity, the instantaneous sediment flux of the graded sand under the action of waves is calculated according to the moving bed velocity and the sediment concentration of different components in the graded sand.

[0108] It should be emphasized here that, in a specific embodiment, before calculating the instantaneous sediment flux of graded sand under wave action based on the flow velocity of the moving bed surface and the sediment concentration of different components in the graded sand, in order to more accurately reflect the vertical exchange of sediment between the free sand-containing layer, the sand storage layer and the immovable sand-containing layer, this embodiment classifies the graded sand moving bed surface and the graded sand components according to the erosion depth of the graded sand moving bed surface and the sediment amount of different components in the graded sand.

[0109] Specifically, the moving bed of graded sand is divided into a free sand-containing layer, a sand storage layer and an immovable sand-containing layer, and the graded sand components are divided into a first-class graded sand component and a second-class graded sand component.

[0110] It should be noted that for the free sand layer, z>-Δ; for the sand storage layer, -max(Δ i )<z≤-Δ; For the immovable sandy layer, it satisfies z≤-max(Δ i ).

[0111] Among them, Δ i is the sediment content of component i in the graded sand, Δ is the erosion depth of the graded sand moving bed, max(Δ i ) for all Δ i The maximum value in .

[0112] It should also be noted that graded sand movement only exists in the free sand-bearing layer and storage sand, and graded sand sediment flux only exists in the free sand-bearing layer.

[0113] The sediment volume of the first graded sand component is greater than the erosion depth of the graded sand moving bed surface, and the sediment volume of the second graded sand component is less than or equal to the erosion depth of the graded sand moving bed surface.

[0114] According to the moving bed flow velocity and the sediment concentration of different components in the graded sand, the instantaneous sediment flux of the graded sand under the action of waves is calculated. Specifically, firstly, according to the moving bed flow velocity, the sediment concentration of different components in the graded sand and the type of the moving bed of the graded sand, the instantaneous sediment flux of different components in the graded sand is calculated. Then, according to the instantaneous sediment flux of different components in the graded sand, the instantaneous sediment flux of the graded sand under the action of waves is calculated.

[0115] In a specific embodiment, the instantaneous sediment flux of the first graded sand component is calculated by the following formula:

[0116]

[0117] The instantaneous sediment flux of the second graded sand component can be calculated by the following formula:

[0118]

[0119] Among them, Q i1 is the instantaneous sediment flux of the first graded sand component, z is the vertical coordinate, z = 0 is the initial bed surface, t is the time, u B is the velocity of the moving bed, C i is the sediment concentration of component i in the graded sand, Δ is the erosion depth of the graded sand moving bed, Q i2 is the instantaneous sediment flux of the second graded sand component, Δ i is the sediment content of component i in the graded sand, C m is the maximum volume concentration.

[0120] By simplifying the above equations (15) and (16), we can obtain the following equations (17) and (18), which correspond to the calculation of instantaneous sediment flux of the first-class graded sand component and the second-class graded sand component, respectively.

[0121] Specifically, the instantaneous sediment flux of the first graded sand component can be calculated by the following formula:

[0122]

[0123] The instantaneous sediment flux of the second graded sand component can be calculated by the following formula:

[0124]

[0125] On the basis of calculating the instantaneous sediment flux of different components in the graded sand, the instantaneous sediment flux of the graded sand under the action of waves can be further calculated. Specifically, the instantaneous sediment flux Q of the graded sand can be calculated by the following formula:

[0126]

[0127] Among them, Q i Including Q i1 and Q i2 , are the instantaneous sediment fluxes of different components in graded sand.

[0128] In this embodiment, the amount of sediment of different components in the graded sand is calculated according to the sediment settling velocity, exposure and hiding factor, and the phase difference parameter, and the sediment concentration of different components in the graded sand is calculated according to the amount of sediment of different components in the graded sand, and the erosion depth of the moving bed of the graded sand is determined. Then, the moving bed flow velocity is calculated according to the erosion depth of the moving bed of the graded sand and the thickness of the wave boundary layer, and thus the instantaneous sediment flux of the graded sand under the action of waves is calculated according to the moving bed flow velocity and the sediment concentration of different components in the graded sand. This method is designed and calculated by obtaining parameters such as sediment settling velocity, exposure and hiding factors, phase difference parameters, and wave boundary layer thickness. It can calculate the instantaneous sediment flux of each component in the graded sand and the total instantaneous sediment flux of the graded sand. This process can not only reflect the exposure and hiding effects between different components in the graded sand, but also reflect the time response of the sediment flux relative to the hydrodynamic conditions and the net flow caused by the asymmetry of the boundary layer, avoiding the incorrect estimation of the instantaneous sediment flux of the graded sand and further improving the estimation accuracy of the instantaneous sediment flux of the graded sand.

[0129] In addition, in a specific embodiment, an application example of a method for determining instantaneous sediment flux of graded sand under wave action is provided.

[0130] Expanded, given a standard atmospheric pressure, 20°C water temperature, T = 5s, N = 2, d1 = 0.15mm, d2 = 0.51mm, p1 = 0.5, p2 = 0.5, d m =0.33mm,σ g =2.29, s=2.65, g=9.8m / s2, ν=1.0*10-6m2 / s, using the second-order Strokes reciprocating flow velocity, that is, u(t)=1.2cos[2π(t / T-0.214)]+0.3cos[4π(t / T-0.214)].

[0131] First, calculate the sediment settling velocity w corresponding to d1 and d2 i and expose the hidden factor ηi .

[0132] Specifically, according to the above formula (1), w1=0.018m / s, w2=0.059m / s can be calculated; according to the above formula (2), η1=0.71, η2=1.40 can be calculated.

[0133] Then, calculate the wave track amplitude A and the roughness k of the moving bed surface N , d1 and d2 corresponding to the Scherz number Θ i and the wave friction factor f.

[0134] Specifically, according to the above formulas (6)-(9), we can know f, θ i , A and k N The calculation result of .

[0135] Expanded, Figure 2 The diagram shows the changes of the wave track amplitude, the roughness height of the moving bed surface, the Schertz number and the wave friction factor within the wave cycle provided by the present invention.

[0136] exist Figure 2 In the equation, t / T is the dimensionless time, A / A m is the dimensionless wave orbit amplitude, k / k Nm is the dimensionless roughness height of the moving bed, Θ1 and Θ2 are the Scherz numbers corresponding to d1 and d2 respectively.

[0137] Then, calculate the phase difference parameter φ corresponding to d1 and d2 i , β 1i and β 2i .

[0138] Specifically, according to the above formula (3), φ1=0.51, φ2=0.20 can be calculated; according to the above formula (4), β 11 =2.16, β 12 =1.17; According to the above formula (5), β can be calculated 21 =1.04,β 22 =2.03.

[0139] Next, the erosion depth Δ of the graded sand moving bed and the thickness of the wave boundary layer δ are calculated. B And the sediment volume Δ corresponding to d1 and d2 i .

[0140] Specifically, according to the above formulas (10), (11) and (13), corresponding calculation results can be obtained.

[0141] Expanded, Figure 3The diagram shows the change of the erosion depth of the moving bed of the graded sand provided by the present invention, the thickness of the wave boundary layer and the amount of sediment of different components in the graded sand within the wave cycle.

[0142] exist Figure 3 In the equation, z is the vertical coordinate, z = 0 is the initial bed surface, t / T is the dimensionless time, δ B / δ Bm is the dimensionless wave boundary layer thickness, Δ1 and Δ2 are the sediment amounts corresponding to d1 and d2, respectively.

[0143] Then, calculate the moving bed surface velocity u B And the sediment concentration C corresponding to d1 and d2 i .

[0144] Specifically, the corresponding calculation results can be obtained according to the above formulas (12) and (14).

[0145] Expanded, Figure 4 A schematic diagram showing the flow velocity of the moving bed surface provided by the present invention and the sediment concentration corresponding to different components in the graded sand within a wave cycle is shown.

[0146] exist Figure 4 In, due to u B and C i Varies with time and location, Figure 4 Only the cycle-averaged results, i.e., the cycle-averaged flow velocity and the cycle-averaged sediment concentration of each component in the graded sand, are shown.

[0147] z is the vertical coordinate, z=0 is the initial bed surface, C1 and C2 are the sediment concentrations corresponding to d1 and d2 respectively, and the angle brackets represent the period average value.

[0148] Finally, calculate the instantaneous sediment flux Q corresponding to d1 and d2 i and instantaneous sediment flux Q of graded sand.

[0149] Specifically, according to the above formulas (15)-(16), (19) or (17)-(19), corresponding calculation results can be obtained.

[0150] Expanded, Figure 5 The schematic diagram shows the changes of the first graded sand component and the second graded sand component provided by the present invention within the wave cycle, and Figure 6 The diagram shows the change of instantaneous sediment flux of graded sand provided by the present invention within a wave cycle.

[0151] exist Figure 5 In the figure, z is the vertical coordinate, z = 0 is the initial bed surface, t / T is the dimensionless time, Q1 (i.e., Q described above) i1 ) and Q2 (i.e., Q described abovei2 ) are the instantaneous sediment fluxes corresponding to d1 and d2 respectively.

[0152] exist Figure 6 In the equation, z is the vertical coordinate, z = 0 is the initial bed surface, t / T is the dimensionless time, and Q is the instantaneous sediment flux of graded sand.

[0153] in addition, Figure 7 The diagram shows the change of the sediment amount of different components and the period average sediment concentration in the graded sand with the gradation effect removed provided by the present invention within the wave cycle.

[0154] exist Figure 7 In the figure, z is the vertical coordinate, z = 0 is the initial bed surface, t / T is the dimensionless time, Δ1 and Δ2 are the sediment amounts corresponding to d1 and d2, respectively, C1 and C2 are the sediment concentrations corresponding to d1 and d2, respectively, and the angle brackets represent the period average.

[0155] By comparison Figure 3 , Figure 4 and Figure 7 It can be seen that under the grading effect, the amount of moving sediment in the fine component decreases, while the amount of moving sediment in the coarse component increases, which further leads to the periodic average sediment concentrations of the two being closer.

[0156] It should be emphasized that, by adopting the method for determining the instantaneous sediment flux of graded sand under wave action provided by the present invention, the instantaneous sediment flux of graded sand fully considers the grading effect, phase difference and boundary layer asymmetry.

[0157] Compared with the existing method for determining instantaneous sediment flux of graded sand, the present invention has the following advantages:

[0158] On the one hand, the present invention can embody the selective transport of different components in graded sand.

[0159] That is, the present invention takes into account the grading effect by calculating the sediment settling velocity and the exposure hidden factor, which can reflect the mutual influence between different components and reflect the promoting effect of fine components on coarse components and the inhibiting effect of coarse components on fine components.

[0160] Under the grading effect, the amount of moving sediment in the fine component decreases, while the amount of moving sediment in the coarse component increases, which further leads to a closer periodic average sediment concentration between the two.

[0161] On the other hand, the present invention can calculate the instantaneous sediment flux of different components.

[0162] That is, the present invention divides the graded sand bed into a free sand-bearing layer, a sand storage layer and an immobile sand-bearing layer. Sediment movement exists in the free sand-bearing layer and the sand storage layer, and sediment flux exists in the free sand-bearing layer. By calculating the instantaneous sediment flux of each component in the graded sand respectively, the net flux size and direction of sediments of different particle sizes on the graded sand coast under the action of waves can be accurately calculated.

[0163] In addition, the present invention can also reflect the phase difference of sediment movement under the action of waves and the net flow caused by the asymmetry of the boundary layer.

[0164] The present invention can reflect the time response required for sediment flux relative to hydrodynamic conditions by calculating the phase difference parameter, and consider the asymmetry of the boundary layer by calculating the wave boundary layer thickness, thereby reflecting the net flow caused by the asymmetry of the boundary layer.

[0165] Figure 8 The schematic diagram of the structure of the device for determining the instantaneous sediment flux of graded sand under the action of waves provided by the present invention is shown.

[0166] like Figure 8 As shown, the device includes: a data acquisition module 810, which is used to obtain the sediment settling velocity, exposure and hiding factors, phase difference parameters and wave boundary layer thickness of different components in the graded sand; an instantaneous sediment flux calculation module 820, which is used to calculate the instantaneous sediment flux of the graded sand based on the sediment settling velocity, exposure and hiding factors, phase difference parameters and wave boundary layer thickness.

[0167] In this embodiment, the sediment settling velocity, exposure and concealment factor, phase difference parameter and wave boundary layer thickness of different components in the graded sand are obtained by the data acquisition module 810, and the instantaneous sediment flux calculation module 820 calculates the instantaneous sediment flux of the graded sand based on the sediment settling velocity, exposure and concealment factor, phase difference parameter and wave boundary layer thickness. The device is designed and calculated by obtaining parameters such as sediment settling velocity, exposure and concealment factor, phase difference parameter and wave boundary layer thickness, and can calculate the instantaneous sediment flux of each component in the graded sand and the total instantaneous sediment flux of the graded sand. This process can not only reflect the exposure and concealment effect between different components in the graded sand, but also reflect the time response of the sediment flux relative to the hydrodynamic conditions and the net flow caused by the asymmetry of the boundary layer, thereby avoiding the wrong estimation of the instantaneous sediment flux of the graded sand and further improving the estimation accuracy of the instantaneous sediment flux of the graded sand.

[0168] It should be noted that the device for determining the instantaneous sediment flux of graded sand under wave action provided in this embodiment and the method for determining the instantaneous sediment flux of graded sand under wave action described above can correspond to each other and will not be described in detail here.

[0169] Fig. 9An example of a physical structure diagram of an electronic device is shown in FIG. Fig. 9 As shown, the electronic device may include: a processor 910, a communication interface 920, a memory 930 and a communication bus 940, wherein the processor 910, the communication interface 920 and the memory 930 communicate with each other through the communication bus 940. The processor 910 may call the logic instructions in the memory 930 to execute a method for determining the instantaneous sediment flux of graded sand under the action of waves, the method comprising: obtaining sediment settling velocity, exposure and concealment factor, phase difference parameter and wave boundary layer thickness of different components in the graded sand; and calculating the instantaneous sediment flux of the graded sand based on the sediment settling velocity, exposure and concealment factor, phase difference parameter and wave boundary layer thickness.

[0170] In addition, the logic instructions in the above-mentioned memory 930 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0171] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, it is implemented to execute the method for determining the instantaneous sediment flux of graded sand under the action of waves provided by the above-mentioned methods. The method includes: obtaining the sediment settling velocity, exposure and hiding factor, phase difference parameter and wave boundary layer thickness of different components in the graded sand; based on the sediment settling velocity, exposure and hiding factor, phase difference parameter and wave boundary layer thickness, calculating the instantaneous sediment flux of the graded sand.

[0172] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0173] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0174] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for determining the instantaneous sediment flux of graded sand under wave action, characterized in that: include: Obtain sediment settling velocity, exposure and hiding factors, phase difference parameters and wave boundary layer thickness of different components in graded sand; Based on the sediment settling velocity, exposure and concealment factor, phase difference parameter and wave boundary layer thickness, the instantaneous sediment flux of graded sand is calculated.

2. The method for determining instantaneous sediment flux of graded sand under wave action according to claim 1, characterized in that: The instantaneous sediment flux of graded sand is calculated based on the sediment settling velocity, exposure and concealment factor, phase difference parameter and wave boundary layer thickness, including: Calculating the sediment amounts of different components in the graded sand according to the sediment settling velocity, exposure and concealment factor, and phase difference parameter; According to the sediment amount of different components in graded sand, the sediment concentration of different components in graded sand is calculated, and the erosion depth of the moving bed of graded sand is determined; Calculating the flow velocity of the moving bed surface according to the erosion depth of the graded sand moving bed surface and the thickness of the wave boundary layer; The instantaneous sediment flux of the graded sand under the action of waves is calculated according to the moving bed surface flow velocity and the sediment concentrations of different components in the graded sand.

3. The method for determining instantaneous sediment flux of graded sand under wave action according to claim 2, characterized in that: The method of calculating the instantaneous sediment flux of the graded sand under the action of waves according to the moving bed surface velocity and the sediment concentration of different components in the graded sand includes: Classifying the graded sand moving bed and graded sand components according to the erosion depth of the graded sand moving bed and the amount of sediment of different components in the graded sand; The categories of the graded sand moving bed surface include free sand-containing layer, sand storage layer and immovable sand-containing layer, and the graded sand components include first-type graded sand components and second-type graded sand components.

4. The method for determining instantaneous sediment flux of graded sand under wave action according to claim 3, characterized in that: The step of calculating the instantaneous sediment flux of the graded sand under the action of waves according to the moving bed surface velocity and the sediment concentrations of different components in the graded sand comprises: Calculating instantaneous sediment fluxes of different components in the graded sand according to the moving bed surface flow velocity, sediment concentrations of different components in the graded sand, and the type of the moving bed surface of the graded sand; According to the instantaneous sediment flux of different components in the graded sand, the instantaneous sediment flux of the graded sand under the action of waves is calculated.

5. The method for determining instantaneous sediment flux of graded sand under wave action according to claim 4, characterized in that: The instantaneous sediment flux of the first graded sand component is calculated by the following formula: The instantaneous sediment flux of the second graded sand component is calculated by the following formula: Among them, Q i1 is the instantaneous sediment flux of the first graded sand component, z is the vertical coordinate, t is the time, u B is the velocity of the moving bed surface, C i is the sediment concentration of component i in the graded sand, Δ is the erosion depth of the graded sand moving bed, Q i2 is the instantaneous sediment flux of the second graded sand component, Δ i is the sediment content of component i in the graded sand, C m is the maximum volume concentration.

6. The method for determining instantaneous sediment flux of graded sand under wave action according to claim 5, characterized in that: The moving bed surface flow velocity u B Calculated by the following formula: Among them, u is the velocity of the outer boundary layer, u0 is the velocity amplitude of the outer boundary layer, r is the nonlinear index, δ B is the thickness of the wave boundary layer, t0 is the parameter that makes u(0) = 0, α = 2π / T is the frequency, is the waveform parameter; The sediment concentration C of the graded sand components i Calculated by the following formula:

7. The method for determining instantaneous sediment flux of graded sand under wave action according to claim 6, characterized in that: The wave boundary layer thickness δ B It is obtained by the following calculation formula: d B =0.09A 0.82 k N 0.18 Where A is the orbital amplitude of the wave, k N It is the roughness height of the graded sand moving bed.

8. A device for determining instantaneous sediment flux of graded sand under wave action, characterized in that: include: Data acquisition module, used to obtain sediment settling velocity, exposure and concealment factor, phase difference parameter and wave boundary layer thickness of different components in graded sand; The instantaneous sediment flux calculation module is used to calculate the instantaneous sediment flux of graded sand based on the sediment settling velocity, exposure and concealment factor, phase difference parameter and wave boundary layer thickness.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the method for determining the instantaneous sediment flux of graded sand under the action of waves according to any one of claims 1 to 7 is implemented.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for determining the instantaneous sediment flux of graded sand under the action of waves according to any one of claims 1 to 7 is implemented.

Images